#include<stdio.h>
/*int main()
{
    int a = 0;
    int b = 0;
    int c = 0;
    int d = 0;
    int e = 0;
    for(a = 1; a <= 5; a++)
    {
        for(b = 1; b <= 5; b++)
        {
            for(c = 1; c <= 5; c++)
            {
                for(d = 1; d <= 5; d++)
                {
                    for(e = 1; e <= 5; e++)
                    {
                        if(((b == 2) + (a == 3) == 1)
                         &&((b == 2) + (e == 4) == 1)
                         &&((c == 1) + (d == 2) == 1)
                         &&((c == 5) + (d == 3) == 1)
                         &&((e == 4) + (a == 1) == 1)
                        )
                        {
                            if(a * b * c * d * e == 120)
                            {
                                printf("a=%d,b=%d,c=%d,d=%d,e=%d",a,b,c,d,e);
                                break;
                            }
                        }
                    }
                }
            }
        }
    }
    return 0;
}*/
int main()
{
	int killer = 0;
	for(killer = 'a'; killer <= 'd'; killer++)
	{
		
		if((killer != 'a') + (killer == 'c') + (killer == 'd') + (killer != 'd') == 3)
		{
			printf("%c", killer);
		}
	}
	return 0;	
}
